Containers are often pre-treated on an external surface prior to the printing of product information thereupon. One method of such treatment has been accomplished by contacting the surface to be treated with a treating surface, such as an ink blanket, of a rotating treatment device or decorator. A problem encountered with such devices is the tendency of the container surface to slide relative to the treatment surface when the speeds of the two surfaces are not equalized prior to contact. Such sliding may result in less than optimal treatment coverage or, in the case of printing applications, a smearing of the information sought to be conveyed.
One method of equalizing the speeds of a treatment surface and a container surface involves pre-spinning the container prior to contact with the treatment surface. Typically, the container is mounted on a rotatable mandrel during transport through a production line which includes the treatment device. In such production lines, pre-spinning of the container may be accomplished by contacting a circumferential surface of the container or mandrel with a moving surface, such as a belt, so that the belt causes the container to spin.
Prior art pre-spinning devices are typically used with a rotating blanket wheel mounted on a wheel drive shaft. The rotating blanket wheel or decorator has a number of circumferential blanket surfaces adapted to print on an external container surface. Power is taken from the wheel drive shaft through a series of gears to drive a pre-spinning belt which pre-spins the container. First, a drive gear which is mounted on and driven by the wheel drive shaft turns a nylon gear which in turn drives a spur gear. The spur gear is connected to a cross-over shaft which is parallel to and spaced apart from the wheel drive shaft and drives a first timing pulley. The first timing pulley drives a second timing pulley through an interconnected timing belt. Finally, the second timing pulley drives a pre-spin pulley which drives the pre-spin belt thereby spinning the container.
The prior art devices typically have many interconnecting drive components which are relatively expensive and require frequent maintenance. In addition, installation or replacement of the components is a difficult undertaking which typically renders the treatment device unusable for lengthy periods of time. For example, to replace the drive gear, it is necessary to slide the old gear longitudinally over an end of the drive shaft which requires extensive tear down of the treatment device housing.
Thus, there is a need for an apparatus for pre-spinning a container to be treated on an external surface by a treating surface of a rotating treatment device which has fewer interconnecting parts and is therefore relatively less expensive. In addition, there is a need for such a device which can be installed with reduced treatment device down time resulting in further savings.